1. Field of the Invention
The present invention relates to a battery system that includes a battery block that includes a plurality of rectangular batteries arranged in array alignment and cools the battery block with coolant, and in particular to a battery system suitable for a power supply for vehicles such as hybrid cars.
2. Description of the Related Art
In the case of a battery system with a number of rectangular batteries, since the output voltage of the battery system can be high, the battery system is charged/discharged with a large amount of current. In particular, in the case of a battery system used as a power supply device for a vehicle, the battery system is discharged with a large amount of current when the vehicle is accelerating, and the battery system is charged with a large amount of current during regenerative braking or the like. Since the temperature of battery systems rises greatly when the battery systems are charged/discharged with a large amount of current, such battery systems are forcedly cooled by air or coolant. In the case where a battery system is cooled by air, its cooling structure can be simple. However, since the thermal capacity of air is small, it is difficult for air to quickly cool the battery system in the state where its batteries generate a significantly large amount of heat. Also, in this case, there is a disadvantage in that, if the amount of air flow is increased to increase the amount of battery heat reduction, the noise level of the cooling structure increases. In the case of a cooling structure that cools the battery system by forcedly flowing air, there is a disadvantage in that dust in air accumulates on the surface of the battery system so that the cooling efficiency of the cooling system decreases with time. These disadvantages can be eliminated by a cooling structure disclosed in Japanese Publication of Examined Utility Model Application S34-16929 that includes a cooling pipe that is arranged to be thermally coupled to batteries and is cooled by coolant.
Japanese Publication of Examined Utility Model Application S34-16929 discloses the cooling pipe that is arranged between the batteries, which have a rectangular shape and are aligned with each other. The cooling pipe is cooled by cooling water that is fed to the cooling pipe to cool the rectangular batteries. This structure can efficiently cool the rectangular batteries with the cooling water, however, since the cooling pipe is arranged between a number of rectangular batteries, in the case of a battery system with a number of aligned rectangular batteries, the arrangement of the cooling pipe is very complicated.
The present invention has been developed for solving the disadvantage. It is an important object of the present invention is to provide a battery system that can efficiently cool rectangular batteries with a cooling pipe that can be simply arranged.